An impact monitoring system using an array of fibre Bragg grating (FBG) sensors has been established on a wind turbine blade. The effect of the locations and detection capability of the FBG have been investigated. The possibility to identify the location of an impact is also discussed. This preliminary work may shed some light on how to establish an optimal monitoring system with a minimum number of sensors while achieving the acceptable sensitivity and coverage. With such a system, the corresponding strain history and occurrence of local damage can be monitored, thus helping to narrow down the scope of more detailed examination during an overhaul and enabling the integrity of a wind turbine blade to be more reliably assessed and monitored.